The present invention is directed to improved blower housings of the type used in centrifugal or air foil fans. More specifically, the present invention contemplates a blower housing whose radial and axial dimensions are substantially independent of increased cross-sectional area in the discharge path relative to previous blowers and thereby provides a quieter, more efficient blower with increased airflow in the same physical dimensions. For purposes of this invention, the term ‘blower’ also includes fans, impellers and other fluid moving devices.
Previous blowers, such as that shown in U.S. Pat. No. 5,279,515 to Moore et al., include a scroll housing which expands from a cutoff in a continuous and smoothly increasing radial dimension from that cutoff to a discharge outlet. The scroll housing is enclosed by a pair of substantially flat side walls to enclose a blower and to form a discharge plenum. The discharge plenum is outside of the blower's periphery and inside of the scroll housing and sidewalls. The plenum is characterized by a continuously increasing cross-sectional area basically formed by the radial expansion of the scroll housing away from the periphery of the impeller. This discharge plenum is defined by a rectangular footprint in a plane perpendicular to the axis of the blower and having edges tangent to the scroll housing at locations spaced approximately 90° from each other.
U.S. Pat. No. 5,570,996 to Smiley, III shows a variation where the scroll housing has a conformal portion of constant radius preceding the expansion portion of the scroll housing.
It would be desirous to increase the cross-sectional area of the discharge plenum while reducing its surface area without increasing the rectangular footprint.